Abstract
Though some hypotheses have obtained theoretical and empirical supports,
it remains largely unknown in the aspect that how deception increases
orchid fitness. This study used food-deceptive Papilionanthe teres as
experimental material to explore the ecological significance of orchid
deceptive pollination. Deception together with obvious pollinarium
bending increases P. teres fitness by means of decreasing geitonogamy
under the natural conditions. The proportions of full seeds, single
fruit weight and seed weight per fruit after self-pollination and nectar
addition were significantly lower than that after cross-pollination and
natural conditions (all p < 0.05). Seed viability (seed growth and
development rate) after cross-pollination and natural condition were
significantly higher than that after self-pollination and nectar
addition (all p < 0.05). However, there was no significant difference
in all the above parameter values of fruits and seeds between
cross-pollination and natural conditions (all p > 0.05). These results
confirmed that P. teres has high level of genetic load, and
self-fertilization or geitonogamy will cause serious inbreeding
depression. These conclusions support the outcrossing hypothesis that
ecological significance of P. teres deception is to promote outcrossing
and improve the ability of the offspring to adapt to the environment.